In endoscopic sphincterotomy surgery, sphincterotomes, and more specifically papillotomes, are used in conjunction with an endoscope to provide surgical cutting within a patient. For example, a papillotome may be used to partially cut open the duodenum at the Papilla of Vater for treatment such as removal of common bile duct stones which form an obstruction. Unfortunately, major complications can arise from endoscopic sphincterotomy including bleeding, pancreatitis, perforation, and cholangitis. Bleeding is the most common complication and typically results when the retroduodenal artery is cut. This problem is caused by a lack of control of the surgical equipment used by the physician performing the sphincterotomy.
The typical papillotome, such as disclosed in U.S. Pat. No. 4,485,812 to Harada, et al., includes an electrically conductive wire exposed outside of a tube to act as a cutter. A variety of such sphincterotomes with the wire formed in a bow outside the tube are known as "bowstring" or traction-type sphincterotomes. These devices generally are well known and may contribute to the problem previously described. Shortcomings of this type of papillotome are discussed in U.S. Pat. No. 4,474,174 to Petruzzi, rejecting these more conventional papillotome knives as lacking precise control and providing poor control with danger to adjacent structures during cutting. Instead, the Petruzzi patent suggests an alternative approach in which, rather than having a bowed cutting wire, a pre-bent wire knife having a distal tip is advanced inside a single lumen catheter until it projects from a channel cut through the catheter wall at an angle. The wire knife is connected to a control wire which is manipulated to extend and retract the wire knife into engagement with the tissue. The control wire is fabricated from a helical twisted ribbon-shaped wire. The helical twist provides both a passage way through the lumen for the supply of contrast media, and prevents radial collapse of the catheter walls to prevent the lumen from collapsing.
Several other cutting devices have been proposed with a variety of twisted or braided reinforcing wires in the catheter lumen to reinforce against radial collapse and to maintain the lumen open to allow fluids, such as contrast media, to be supplied to the surgical area. Such devices are illustrated in U.S. Pat. No. 4,325,374 to Komiya, in which a coiled spring is utilized to prevent lumen collapse, and U.S. Pat. No. 4,724,836 to Okada, in which a reinforcing wire is disposed in a fluid lumen to prevent collapse of the lumen when the distal tip is bent. Although these various reinforcing wires may be advantageous for preventing collapse of the lumen, they are not directed to solving the problem set forth above regarding uncontrolled cutting.
Examples of prior art devices commercially available prior to the present invention include the Wilson-Cooke wire guided papillotome, model PTG-30-6-NG and the Bard Interventional Products, models 050049-050052. However, none of these wire guided papillotomes has a pre-curved shape memory tip for controlled bending and orientation and are thus susceptible to the problem of uncontrolled cutting.